At least 31 migrants died on Saturday after their boat capsized off the Libyan coast, the main departure point for African refugees. The coast guard rescued some 200 people, but many more remain unaccounted for. That same day, a 10-year-old Afghan boy was reportedly crushed to death on a boat carrying scores of people toward the Greek island of Lesbos. IOM reported an additional eight migrant deaths this weekend on the western Mediterranean route connecting North Africa to Spain.

Although the number of deaths so far this year is lower than 2016′s year-end total of 5,143, the fatality rate has increased. As of Nov. 26, 163,979 migrants had attempted to cross the Mediterranean this year, and approximately 1.9 percent of them had died. A much greater number of migrants tried to cross in 2016, but the fatality rate for the year was 1.4 percent.

Even the 3,033 migrant deaths in the Mediterranean represent only a portion of the overall tragedy: IOM figures show there have been at least 5,124 migrant fatalities worldwide in 2017. Earlier this month, a German newspaper published a list of 33,000 migrants who have died en route to Europe since 1993.

Ciro De Luca / Reuters
In this Nov. 17 photo, people in Italy's Salerno cemetery pay respect to 26 Nigerian women who died while crossing the Mediterranean Sea.

The leading causes of Mediterranean deaths this year were drowning and presumed drowning, followed by unknown causes, dehydration and starvation. For migrants elsewhere in the world, shootings, physical abuse and harsh weather conditions caused scores of fatalities.

More than half of all migrant and refugee deaths over the past four years have occurred during attempts to cross the Mediterranean. In late 2014, Pope Francis suggested the sea was becoming a “vast cemetery.” Its three main routes are particularly treacherous for people attempting to flee war and persecution in overcrowded smuggler boats, which often fail to carry enough water and fuel for long journeys.

On Friday, the IOM called the Mediterranean “by far the world’s deadliest border” for migrants.

“People are still dying at sea in enormous numbers, even after years of seeing this happen repeatedly,” said Eugenio Ambrosi, the organization’s regional director for the European Union, Norway and Switzerland. “We have to ask ourselves: Why is this still happening?”

More Than 3,000 Migrants Have Died Crossing The Mediterranean This Year

Migrant crisis in the Mediterranean

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TOPSHOT - Migrants try to pull a child out of the water as they wait to be rescued by members of Proactiva Open Arms NGO in the Mediterranean sea, some 12 nautical miles north of Libya, on October 4, 2016.
At least 1,800 migrants were rescued off the Libyan coast, the Italian coastguard announced, adding that similar operations were underway around 15 other overloaded vessels. / AFP / ARIS MESSINIS (Photo credit should read ARIS MESSINIS/AFP/Getty Images)